A radio frequency (RF) diplexer is a device that facilitates communication of two different RF signals within two different RF communication bands by a common antenna. For example, with respect to RF receive diplexing, an RF diplexer is configured to receive two different RF receive signals on a common antenna and then route each of the respective RF receive signals to their appropriate ports. With respect to RF transmission diplexing, an RF diplexer is configured to transmit two different RF transmission signals from different ports and route both to the common antenna. In order to facilitate simultaneous diplexing over the antenna, the RF diplexer needs to be designed for operation at both RF communication bands while providing adequate isolation between the different RF communication bands and the different RF signals. Many previously known RF diplexer topologies struggle to provide this isolation, particularly at the high RF communication bands required by modern RF front-ends. Furthermore, while there are tunable RF diplexers that provide diplexing with respect to various combinations of different RF communication bands, these tunable RF diplexers struggle to provide adequate broadband isolation across large portions of the RF frequency spectrum.
Accordingly, RF diplexers are needed that not only provide high isolation but also maintain this high isolation along greater portions of the RF frequency spectrum.